Validation prevents mirroring release to ipv6 registry

[hardys]

When attempting to use oc adm release mirror in an environment where the local registry is only listening on ipv6, it seems there is some validation which prevents using that address in the --to location:

$ oc adm release mirror --insecure=true -a combined-pullsecret--O2zxxDYRKZ --from registry.svc.ci.openshift.org/ipv6/release:4.3.0-0.nightly-2019-12-20-152137-ipv6.1 --to-release-image fd2e:6f44:5dd8:c956:0:0:0:1:5000/localimages/local-release-image:4.3.0-0.nightly-2019-12-20-152137-ipv6.1 --to [fd2e:6f44:5dd8:c956:0:0:0:1]:5000/localimages/local-release-image
error: --to must be a valid image repository: "[fd2e:6f44:5dd8:c956:0:0:0:1]:5000/localimages/local-release-image" is not a valid image reference: invalid reference format

A similar issue exists if you use the IP in the --to-release-image pullspec - replacing the IP with a hostname hard-coded in /etc/hosts appears to work around the issue.

Can this validation be relaxed to allow for ipv6 addresses?

[russellb]

IPv6 may just not be supported at all, but I did spot this:

-to-release-image fd2e:6f44:5dd8:c956:0:0:0:1:5000/localimages/local-release-image:4.3.0-0.nightly-2019-12-20-152137-ipv6.1

Square brackets need to be added around the IPv6 address to separate it from the port number.

[russellb]

This PR reminded me of a discussion I had here: openshift-metal3/dev-scripts#871

where @adambkaplan was saying that IPv6 addresses are not allowed in a pull spec. It sounds like using a hostname is the right thing to do instead.

[adambkaplan]

yep - @dmage first brought this to my attention. Use a hostname

[hardys]

So it seems this may be deliberate ref openshift/openshift-controller-manager#52 ?

[hardys]

Ok, seems weird that we allow ipv4 addresses but not ipv6, but I'll rework to use a hostname instead, thanks!